Crane-movable form systems known variously as climbing form systems and jump form systems are frequently employed to construct vertical concrete walls for mid-rise structures such as buildings and silos. The basic components of such devices, hereinafter referred to as jump form systems, are shown in FIG. 1. and consist of a jump form frame 400 and form assembly 410, with the frame 400 including a work platform bearing member 420 supporting a work platform 430, a vertical frame member 440 bearing against the wall under construction, and a diagonal frame member 450 which, together with the work platform bearing member 420, vertical frame member 440, and in some systems, auxiliary bracing 452, 454, form a truss which is suspended from jump shoes 480 embedded within previously constructed sections or “lifts” of a concrete wall during the construction process. The primary purpose of modern jump form systems is to support a movable roll back carriage 460 which allows workers on the work platform 430 to prepare, strip, and clean the form assembly 410 while suspended from a prior lift, so that a crane is employed only from time to time to hoist the jump form onto a newly constructed lift, or to remove the jump form system after the completion of that portion of the work. Trailing platforms 470 are typically used to allow for post-tensioning, removal of the jump shoes 480, and patching and other finish work, while auxiliary platforms 472 are typically mounted to the form assembly 410 and roll back carriage 460 to allow for access to the upper and top portions of the forms, which are generally approximately one story tall.
While the basic components of jump form systems are simple and well developed, there are several safety and performance-related features in existing jump form systems that are functional, but not necessarily easy to use. For example, as will be described in further detail below, existing jump form systems generally require workers manually install and remove safety pins to secure the jump form frame within the jump shoes during the construction process. Manipulation of the safety pins may require workers to cantilever off the edge of a working platform or reach through narrow gaps in order to access the connection between the jump form frame and the jump shoe, which typically lies underneath the work platform itself. Thus, installation can be difficult, safety pins can be dropped or otherwise lost, and additional safety procedures must be observed. In a similar vein, existing jump form systems tend to use pin-type locking mechanisms to secure the roll back carriage in position during hoisting operations, but these mechanisms provide very little positional granularity so that a mounted form can be locked into only a handful of positions during the hoisting process. This lack of flexibility requires a trial-and-error procedure where the jump form system is suspended within the confines of a jump shoe, the roll back carriage is secured in a position that coarsely distributes weight so that the jump form system is approximately plumb and level, and some further operation such as tilting the form assembly is used to finely distribute weight so that the jump form system can be hoisted within significant rotation or tilt. This procedure consumes valuable crane time, and again additional safety procedures must be observed. In addition, due to the variety of gang form systems and panel form systems available in the market, jump form systems typically include or require the manufacture of specialized form-mounting hardware accessories in order to allow for even a limited number of form systems to be mounted on a jump form system. Thus, there is a need for a jump form system which provides for simplified installation of safety devices, greater flexibility in the positioning and securing of a roll back carriage, and a simplified inventory of system hardware. This need is addressed through the various improvements described below.